420 
VERTEBRATA. 
JERBOAS. 
Alactaga^ and Acontion^ but we shall group them under the single genus, JERBOA, Dipus. These 
animals have the head large and rabbit-like; the ears long and pointed; the eyes full; the tail 
very long, covered with short hair and tufted at the end, this member being used in leaping and 
walking; the fur is soft and delicate ; the fore-feet are very small ; the hind-legs are long, and the 
hind-feet large and strong, and covered Avith hair. They seem expressly designed to live on 
desert wastes, where they are usually found. Four species are known. 
The Gerbo, or Egyptian Jerboa, D. sagitta, seems to have excited the curiosity of man- 
kind from the earliest times. Aristotle speaks of it as an Egyptian rat that walks on two feet, 
and Pliny calls it a wcdking-hiped. In size it is equal to a small rat, the body being five inches 
long and the tail seven ; the general color is a pale tawny-yellow, passing into a lighter tmt, and 
finally into white below. It is found in Egypt, Nubia, parts of Syria, and Barbary, living in troops 
on the arid deserts, digging long burrows in heaps of sand, and often amid crumbling rmns. In 
these burrows they make their nests and rear their young. Their food consists of gTain, bulbous 
roots which they dig up with their fore-paws, and of other vegetables. They hibernate, but are 
dormant for only'a short time. Their flesh is unsavory, but is still eaten. When undisturbed, 
their common manner of sitting is on their haunches, their short fore-paws hanging down like 
those of the Kangaroo. So powerful are their teeth that they speedily gnaw through the hardest 
wood. They are partially nocturnal in their habits, are exceedingly timid, and hasten to their 
burrows upon the slightest alarm. So great is their speed in flying across a plain that they will 
outstrip a greyhound. In making each leap they spring from the hind-feet, the impetus being 
given by the powerful muscles of the thighs, while the tail serves as balance and rudder. So es- 
sential is the tail, that when deprived of it the animal seems to be afraid to leap, and indeed to 
have lost its power. In springing, the fore-paws are pressed close to the breast ; they descend, 
however, upon them at each bound, but such is the celerity of the movement that the eye is de- 
ceived, and the fore-paws seem not to be used at all in the act of running. 
The Dark-banded Jerboa, D. Indicus, is thus described by General Hardwicke : " These ani- 
mals are very numerous about cultivated lands, and are particularly destructive to wheat and bar- 
ley crops, of which they lay up considerable hoards in spacious burrows near the scenes of their 
plunder. They cut the culms of the ripening corn just beneath the ears, and convey them thus 
entire to one common subterraneous repository, which, when filled, they carefully close, and do 
not open for use till supplies abroad become distant and scarce. Grain of all kinds is their favor- 
ite food; but in default of this they have recourse to the roots of grass and other vegetables. 
About the close of day they issue from their burrows, and traverse the plains in all directions to 
